The effects of crude and diesel oil spills on plant communities at Mesters Vig

Crude and diesel oils were spilled on five common Mesters Vig plant communities at an intensity of 10 L m-2. The communities include wet marsh, grassland, and three types of dwarfshrub heath. The reaction of the plant species of the different communities was recorded three successive years after the spills. After the third year the status is as follows: Where crude oil was spilled, the shrubs showed moderate recovery. Salix arctica showed best recovery, whereas Dryas octopetala and Vaccinium uliginosum showed almost no recovery. Graminoids recovered moderately on the wetter plots, but slightly or not at all on the drier plots. Forbs showed no recovery, but in the third year a few seedlings occurred. Mosses showed moderate to good recovery on the wetter plots, but almost no recovery on the drier plots. Generally, the degree of recovery was best in the wet and moist plant communities. In the diesel-oil treated plots, shrubs showed no recovery. Graminoids showed almost no recovery except for Carex bigelowii which recovered moderately. Forbs showed almost no recovery except for a very few seedlings. Mosses recovered moderately in the dry plots and excellently in the wetter plots. Generally, recovery of mosses was better in the diesel plots than in the crude oil plots.